leverage

The ratio that lets a small deposit control a large position; 30:1 means $1,000 controls $30,000 of notional. It is the mechanism that turns a normal price wiggle into a wiped account, which is why retail FX leverage on majors was capped at 30:1 in 2018.

First used in Lesson 1.1 · FX & CFD mechanics: speak broker — the lesson that makes this term real.